Histochemical structure and immunolocalisation of the hyaluronan system in the dromedary oviduct

We investigated the local modulation of some histochemical properties of oviducts of the dromedary (Camelus dromedarius), focusing on the immnolocalisation of hyaluronic acid (HA) synthases (HAS2 and HAS3), hyaluronidases (HYAL2 and HYAL1) and the HA receptor CD44 in the ampulla and isthmus. Abundant acidic mucopolysaccharides (glycosaminoglycans) were detected by Alcian blue staining along the luminal surface of both ciliated and non-ciliated epithelial cells (LE). Staining for HAS2 was higher in the primary epithelial folds of the ampulla compared with the isthmus, especially in secretory cells, adluminal epithelial surface and supranuclear cell domain. HAS3 staining was stronger in the LE of the isthmus than ampulla. HYAL2 was detected in the LE in the ampulla and isthmus and was more intense in the adluminal projections of secretory cells. HYAL1 was weakly detected in the LE with no difference between the ampulla and isthmus. Strong CD44 immunostaining was present in the LE of the ampulla and isthmus. CD44 staining was higher in secretory cells than in ciliated epithelial cells and was higher in the supranuclear region than the basal region of the cytoplasm. In conclusion, we provide evidence that HA synthesis and turnover occur in the camel oviduct. Differences in HAS2 and HAS3 expression suggest regional differences in the molecular size of HA secreted in oviductal fluid that may influence oviduct-gamete interaction in the camel.